I've only recently started incorporating dynamic hair in my renders and was wondering if there's an easy way to calculate it so as to make it easier to have a hat or other head prop as well. Up to now I just used magnets to pull/scale down the parts of the transmapped hair that would stick out but I'm not sure if the collision detection for dynamic hair would work and how. If not, can I still apply magnets to dynamic hair?

Yes, dynamic hair is affected by magnets. And I suppose you could try collisions with a hat, but suspect it'll be a trickish affair. I'm not sure how the hair dynamics will respond to compression.

Thanks, I'll be trying both and reporting back the results :)

Magnets have worked for me on dynamic hair. Also - with clothing (not tried it on hair so I do not know if it works) I will often spawn morphs to help partly pose the clothing like I want it prior to going into the Cloth Room. Might work the same with Hair.

The only time I did dynamic hair with a hat (see "Nice Hat" in gallery), I just made the model bald under the hat but loaded up the hair just above the brim. I think I also once heard a suggestion of doing the hair on the inside of the hat, just above the brim, growing in towards the head. Do collision against the hair and the head (or skullcap) and then lower the hat onto the head during the animation. I've never tried it, but it sounded intriguing.